Exam 4, Chapter 16: Speciation

They are on a trajectory, not at endpoints (Speciation is a process. When you are studying, you are only looking at a snapshot in time.)

When referring to the divergence step of speciation, why do we refer to the divergent species as a subspecies?

interbreed or not

When secondary contact occurs, there are only two options...

adaptive radiation

When speciation is represented in a circular fashion (as shown in the image), we use the phrase __________ __________.

estuarine environments of Asia, Europe, and North America

Where are Marine Copepods found?

east African Rift Valley Lake region

Where are cichlid fished located?

Texas

Where are the Western/Eastern spotted skunks located?

biological species, morphological species, phylogenetic species

Which are the three main species concepts?

Phylogenetic Species Concept

Which concept defines species based on statistical similarities in phylogenetic studies?

cichlid (These fishes are found in many different lakes in the east African Rift Valley Lake region and have different color polymorphism. There is spatial separation - bottom or top of water, some feed differently which creates another barrier, etc.)

A prominent example of sympatric speciation is that of________ fishes.

mating (also accept interbreeding and gene flow)

A reinforcement on speciation is if descendant generations are not _____.

monophyletic, geography (classic allopatry)

Lee et al. clustered populations into ____________ groups based on _________.

common ancestor

All of the species of cichlids came from one ______ _______.

27 (Written about by Wheeler and Meier)

At least ____ species concepts have been proposed and developed!

38

Lee et al. collected copepods from ___ populations across the range.

Oahu

By plotting the phylogeny of Drosophilia against the age of the islands, we can predict that the oldest fruit flies are on _____ and the flies on Maui and the newer islands came from these.

mitochondrial

COI is a ___________ gene.

characters, subjective, speciation

Cons if Phylogenetic Species Concept: 1) unsure which _______ to use (morphology?, molecular?, etc.) 2) __________ (how much divergence in BP differences is enough) 3) does not include a mechanism of ________

cannot be applied with fossil species, does not work for asexually-reproducing species, hybridization presents problems, difficult to ascertain if disjunct sister species *could* reproduce

Cons of the Biological Species Concept

subjective, often relies on expert opinion, difficult to apply to taxa lacking distinctive morphological features, namely prokaryotes

Cons of using the morphological species concept

allopatry

Disjunct Distribution is (loosely) the end product to _________ as a process.

mutations, drift, selection

Divergence in traits is typically due to a combination of what three evolutionary processes?

derived

Divergence yields unique, _________ traits.

unique, apomorphies, taxon

Divergence yields... 1) ______, derived traits 2) these _______ typically further isolate diverging populations 3) a distinct _____ that can conform to several different species concepts

8 (in the image one can see 8 or 3 species depending on how you define the species - this brings in the Biological species concept)

Lee et al. established that there are _____ species of copepods.

16S rRNA and COI

Lee et al. sequences the copepods _______ and _____ genes.

populations

Each of the letters represent ______.

postzygotic (these species are considered reproductively isolated because their offspring are not fit or cannot reproduce again)

Factors that are prohibitive to mating that arise AFTER mating.

prezygotic

Factors that are prohibitive to mating that arise BEFORE mating.

Postzygotic

Form of reproductive isolation that occurs after mating, typically forming offspring that either have very low fitness or are sterile.

prezygotic

Form of reproductive isolation that occurs prior to mating due to differences in mate recognition, life history traits, reproductive timing, morphological incompatibility, egg incompatibility, etc.?

phylogenetic species concept

Lee et. al used what concept to determine the speciation of marine copepods?

gene flow

Genetic isolation results in a reduction of _______ ______ between populations.

synapomorphic feature

How do you know/define a monophyletic group?

1.5 million (approximately)

How many formally described species exist?

3, 9

How many species is/are represented by this phylogeny? How many populations?

autoapomorphic

If a derived trait is only in one descendent lineage it is referred to as __________.

They are distinct species.

If secondary contact occurs and no viable interbreeding occurs, what can be inferred?

complete, incomplete

If secondary contact occurs, two outcomes are possible, 1) Reproductive isolation is _________, through process of reinforcement (e.g., assortative mating, hybrid infertility) 2) Reproductive isolation is ___________. Viable hybrids form between subpopulations and admix back into one unit (gene flow re-established)

independent trajectories.

If they are isolated and independent, the two populations are on ___________ __________.

Phylogenetic species concept

If you are looking at where the species are found to determine if they are distinct, you are using which concept?

farthest, closest

If you plot volcanoes as a product of distance from the hotspot, you can see the the oldest volcanoes are (CLOSEST/FARTHEST) from the hotspot and the newer volcanoes are (CLOSEST/FARTHEST)

Endangered Species Act

The biological species concept is used to aid in defining species protected under the ________ _________ _____

divergence

Independent accumulation of differences caused by evolutionary processes is known as _______.

interbreed

Independent evolution of allele frequencies cause enough divergence that subpopulations may no longer viably _________.

Alabama (This is a huge difference for a species that distributes poorly.)

Mammoth cave shrimp has a sister species in northern ______.

Vicariance (Starting with one large population that slowly and gradually dissects into units; Genetic drift could occur if one population is huge and the other is small.)

Mode of isolation in which a splitting of a species into separate populations occurs by formation of a geographic barrier.

Dispersal (In the context of allopatry, this movement must result in physical isolation.)

Mode of isolation involving a movement or expansion of a population into a new area

Biological Species Concept

Most commonly applied species concept

evolutionarily independent

New subpopulations eventually have ____________ ___________ trajectories and will undergo divergence of allele frequencies and are reinforced with time

sympatric speciation

No spatial separations, but barriers to gene flow do occur (barriers can form due to differences in life cycles and polyploidy)

incapable

Once subpopulations are (CAPABLE/INCAPABLE) of reproducing with each other, they are considered separate entities and "distinct species"

Angiosperms (Angiosperms have a high tendency to hybridize so it is difficult to determine the separate species)

One of the cons of using the biological species concept is hybridization presents problems. What is an example of this?

decrease

Panthers and Black Bears in the Everglades have experienced a(n) (INCREASE/DECREASE) in size.

evolutionary, monophyly, broadly

Pros of the Phylogenetic Species Concept: 1) inline with ________ theory 2) identifies species on the basis of ________ (the members of a monophyletic group) - the cornerstone of phylogenetic theory 3) much more _______ applied than MSC or BSC

easily applied, makes intuitive sense

Pros of the biological species concept

easily applied, makes intuitive sense

Pros of using the morphological species concept

False (These skunks used to be considered subspecies due to the isolation between the populations, but now they are considered separate species and cannot interbreed.)

True or False: Western Spotted Skunks and Eastern Spotted skunks may occupy different areas of Texas, but are still part of the same species.

False (egg incompatibility is a pre zygotic reinforcer)

True or false: An example of post zygotic reinforcement of reproductive isolation is egg incompatibility.

divergence

Reproductive isolation reinforces ________.

Morphological species concept

Says that different morphologies will form and persist only if gene flow is restricted (genetic isolation is assumed)

common most recent ancestor

Sister species share a ...

branching

Speciation is a ________ process of divergence

isolation, divergence, isolation

Speciation models generally include three stages: 1) ________ of populations 2) __________ in traits 3) reproductive _______

evolutionary, biological, define, distinct, right

Summary of Species concepts: 1) products of _________ processes 2) basic units of _________ diversity 3) they are often hard to ________ 4) not always ______ (often "grading" into one another across larger "areas") 5) no "______" concept ( all have pros and cons) 6) different concepts are used for different reasons by different people

nestedness, monophyletic, disjunct distributions

Summary of speciation: 1)There is _________ in biological diversity 2) __________ groups can be identified 3) sister species often have ________ __________

evolution

Taxa are not evolving unless at least one mechanism of _________ is at play.

tectonic forces (volcanoes)

The Hawaiian islands are formed via ______ _______.

Andes (This mountain range found in South America forms an East-West Barrier.)

The ______ represent a giant barrier to dispersal.

Snapping Shrimp

The common name for Genus Alpheus (250 spp.)

disjunct distribution

The difference in representative area between the Mammoth Cave Shrimp and its sister species in Northern Alabama is representative of a ________ _______.

gene flow (This is not incorporated into the morphological species concept because gene flow only involves one taxa)

The morphological species says that different appearances evolve when populations experience all forms of evolutionary mechanisms *except for* ...

one ancestor and two descendants.

The most parsimonious solution is always...

Speciation

The process in which new species form by divergence of populations of an existing species

True

True or false: An example of pre zygotic reinforcement of reproductive isolation is mate recognition differences.

1,600

There are ______ cichlid fishes in Africa alone.

cryptic speciation

These species are identical in appearance, but are genetically different.

Mammoth Cave Shrimp

This is an endemic micro-crustacean found at Mammoth Cave National Park. It is very small and blind. It is only known in this area.

BSC (Biological Species Concept)

This model is the classic hypothesis to speciation.

Morphological species concept

This states that species (and other ranks) can be diagnosed and differentiated based on consistent morphological differences

False (5% divergence is a large estimate, so the 6.5 to 19% is a huge divergence seen in Snapping shrimp. This indicates a huge amount of speciation.)

True or False: 5% divergence is relatively low in relation to size of populations.

True (using molecular data to determine that the species were separated into different geographic regions)

True or False: All species concepts can be used in synchrony.

False (The Hawaiian islands are formed at the Hawaiian hotspot and as they age and more are formed they move in the northwest direction. So the newest island is closest to the hotspot, and the oldest is the farthest northwest.)

True or False: As the Hawaiian islands age, they move Southeast. The youngest Hawaiian island is therefore at the center of the Hawaiian hotspot.

False (While this is the typical case, it is not absolute.)

True or False: Barriers are always geographic.

False (Sometimes barriers are large, and sometimes they are subtle)

True or False: Barriers between populations are always relatively large as is represented by the East-West Barrier created by the Andes.

False (While the black bears in Florida may be morphologically different than an Alaskan Black Bear, but they would still interbreed if given the opportunity. They are not a distinct species, but just separated.)

True or False: Due to the difference in size and the distance between the two, Floridian and Alaskan black bears are reproductively isolated and considered a distinct species.

False (They were considered one species due to the morphospecies concept - they all look alike

True or False: Marine copepods were traditionally considered one species based on the biological species concept.

False (New species are created from populations, because evolution operates at the population level.)

True or False: New species can be created from an individual if the conditions are optimal for that individual's fitness

True

True or False: Reinforcement of reproductive isolation typically occurs when traits or mechanisms develop that prevent subpopulations from mating.

True

True or False: Speciation is a process.

False (Horses and donkeys can reproduce, but make sterile offspring. This leads to theoretical reproductive isolation. So they are still separate species.)

True or False: Though they go by different titles, horses and donkeys are of the same species as can be concluded from their success in mating.

False (vicariance and dispersal operate together)

True or False: Vicariance and Dispersal act as completely independent units.

species, important

Two questions to consider in regards to speciation: 1) What is a _______? 2) Why are they _______?

geography

Using the phylogenetic species concept and the data from the gene sequences, Lee et al. concluded that the populations of copepods were clustered together because of ________.

fruit flies (Drosophilia)

Variations of this insect species are found on all the Hawaiian islands?

membrane proteins

What allows gametes to recognize each other and prevent recombination between unlike species?

Dispersal, Vicariance

What are the two modes of isolation?

prezygotic, postzygotic

What are the two types of traits/mechanisms that prevent subpopulations from mating

There are two species of African elephants (a unique DNA sequence differentiates the two species, and there are multiple populations of each species)

What can be inferred about African Elephants?

Dispersal (The barrier must be substantial in this case or gene flow would occur from individuals going back and forth; this is known as the Founder Effect if the genetic makeup of the founders is by chance alone unlike the average genetic makeup of the parent population.)

What is it called when a few individuals from one large parental population disperse?

genetic compatibility between populations (if organisms cannot produce viable offspring, they are considered distinctive species due to no gene flow; this is not a good test because you have no way of knowing if your experimental conditions are appropriate)

What is the "test" relating to the biological species concept?

the plains

What is the barrier between Hemlock trees of the Appalachian and those of the Rocky mountains?

5-100 million

What is the estimate for global species richness?

It shows evolution as a linear process (Evolution is not linear, it is a branching process, as is speciation)

What is wrong with this picture?

Isthmus of Panama

What land barrier created a dispersal barrier between Snapping Shrimp?

Savannah elephants have more dispersed populations, while Forest elephants are in the same area (The dispersal between Savannah elephants is not indicative of different species, simply different populations)

What pattern is seen here?

insects, arachnids, flowering plants

What three groups contain the most species?

six, two

When looking at the Seaside Sparrow, one can describe ____ species based on morphology and song, but it is currently accepted that there are _____ species based on DNA sequence.

Charles Darwin, Descent of Man (1871 - this statement has not been changed)

Who defined a species as "... It is a hopeless endeavour to decide this point on sound grounds, until some definition of the term "species" is generally accepted; and the definition must not include an element that cannot possible be ascertained, such as an act of creation..." and in what book was it written?

Charles Darwin, Origin of Species (1859)

Who defined a species as "... No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of a species. Generally the term includes the unknown element of a distinct act of creation..." and in what book was it written?

Joel Cracraft

Who defined a species as "...smallest diagnosable monophyletic group of populations with distinct patterns of ancestry and descent"

Ernst Mayr

Who is most responsible for the Biological species concept?

Joel Cracraft (1983)

Who represents the Phylogenetic Species concept?

Lee

Who researched allopatry in copepod?

Ernst Mayr (1940)

Who stated that "...species are groups of actually or potentially interbreeding populations that are reproductively isolated from other groups..."?

many taxa are poorly studied (especially microbes and organisms with unaesthetic properties such as roundworms), many regions have been poorly sampled (namely in tropical climates)(BUT, molecular methods are increasingly discovering more "cryptic" species)

Why does such a large range exist in regards to global species richness?

large geographic barrier

Why was divergence in snapping shrimp reinforced?

strongly, selection

With differences in environmental pressures, the new subpopulation formed from divergence may be (STRONGLY/WEAKLY) influenced by _________.

disjunct distributions (varying distributions, they are often allopatric)

With regard to speciation, sister species often have _______ _______.

nestedness (hierarchies)

With regard to speciation, there is ___________ in biological diversity.

The other regions differ in that they are islands (but this is not representative of a unique species, just different populations)

With regard to the representation of Asian Elephants, what can be said about the distribution among India and the other regions?

8

_____ allopatric species pairs were found in Snapping Shrimp

allozymes, mitochondrial DNA

______ and ______ were sequenced in snapping shrimp to determine the number of species pairs present.

Genetic drift

_________ _______ is more likely to act on a small group which can lead to independence of populations.

Speciation (what you are studying is just a snapshot of time - you are only reporting what is seen at this moment in time)

_________ takes place over time.

population, genetic

__________ isolation leads to ________ isolation if there is no gene flow

mutations, selective pressures, evolve

genetic isolation establishes independence of populations to... 1) accumulate their own _________ 2) adapt to specific ________ ________ 3) ________ along independent trajectories

allopatric

occurring in separate, non-overlapping areas

allopatric species

process by which related species are rendered distinct; isolation creates a barrier (typically geographic) to gene flow

speciation

process in which new species form by *divergence* of *populations* of an existing species